Dilys Laye and Sid James in Carry On Cruising.
Photograph: Allstar/CARRY ON LINE/STUDIOCANAL

Even on a £4,800 trip of a lifetime, a holidaymaker doesn’t expect this. A UK couple are seeking compensation after saying they boarded a cruise ship sailing from Singapore to Phuket to find another man and woman in flagrante in their designated cabin.

Bobby and Mary Jackson, aged 64 and 62, from County Antrim, Northern Ireland, were offered £200 each off their next journey with Norwegian Cruise Line. Mrs Jackson told the Sunday Post: “I was traumatised and I needed a glass of water.” Mr Jackson concurred: “We are not prudes but this was ridiculous.”

Lisa Niver, a travel journalist and former cruise ship crew member, said the Jacksons’ experience was “outrageous”. In her seven years’ experience on a number of lines (though not Norwegian), she said many crew did not have passenger deck privileges at all. “When I worked onboard, the rules were very clear and strict. Breaking the rules had severe punishments including being fired or turned over to local authorities, both of which I saw happen during my years at sea.”

The culprit was reported to be a crew member, abetted by a “mystery woman” – although in a twist, Norwegian say video footage (presumably outside the cabin) does not corroborate the Jacksons’ version of events. But the story has thrust forward questions of just what goes on onboard these ships.

While the cost and nature of many cruises keeps them firmly populated by well-heeled passengers of advancing years, ships catering for a younger and drunker clientele have become well established, particularly in the US and Australia. For a certain kind of crew member, the promise of working and playing hard has appeal. As Brian Bruns, a waiter turned author of Cruise Ship Confidential, recalls of finishing a 16-hour shift: “It’s like you just came off the frontline. What do you do? You hammer shots so you pass out asap.”

Those crew members with the energy for liaisons, after months at sea without a day off, might well prefer a passenger’s stateroom to their own quarters below deck, where those sub-officer class typically bunk up with three others in a cabin. And while younger western crew might work as entertainers or in customer-facing roles, the hardest graft is often done by lower-paid labourers. In international waters, aboard ships carrying thousands of crew, let alone passengers, anything goes.

But the horror that the Jacksons say they were presented with by the Norwegian crew member – described only as “sheepish” – was essentially one of bad timing. Perhaps the real takeaway of their story is that no one sold on the brochures of azure waters and round-the-clock service wishes to be confronted too vividly with the reality: that the bed booked for a dream holiday will have been all too recently occupied, for better or worse, by another.